U.S. patent application number 14/204847 was filed with the patent office on 2014-09-18 for solid state imaging device and manufacturing method, and electronic apparatus.
This patent application is currently assigned to Sony Corporation. The applicant listed for this patent is Sony Corporation. Invention is credited to Hiroaki Seko.
Application Number | 20140264694 14/204847 |
Document ID | / |
Family ID | 51523794 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140264694 |
Kind Code |
A1 |
Seko; Hiroaki |
September 18, 2014 |
SOLID STATE IMAGING DEVICE AND MANUFACTURING METHOD, AND ELECTRONIC
APPARATUS
Abstract
A solid state imaging device includes a substrate, in which the
substrate includes a photoelectric conversion unit that generates a
charge according to a light amount of incident light by a pixel
unit, an accumulation unit that divides the charge of the pixel
unit which is generated in the photoelectric conversion unit and
accumulates the charge, a first element isolation unit that is
formed at a boundary of the photoelectric conversion unit of the
pixel unit, and a second element isolation unit that is formed at a
boundary of the accumulation unit of a divided unit of the
pixel.
Inventors: |
Seko; Hiroaki; (Kanagawa,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sony Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Sony Corporation
Tokyo
JP
|
Family ID: |
51523794 |
Appl. No.: |
14/204847 |
Filed: |
March 11, 2014 |
Current U.S.
Class: |
257/432 ;
257/446; 438/73 |
Current CPC
Class: |
H01L 27/14627 20130101;
H01L 27/1464 20130101; H01L 27/14685 20130101; H01L 27/1463
20130101; H01L 27/14621 20130101; H01L 27/14687 20130101 |
Class at
Publication: |
257/432 ; 438/73;
257/446 |
International
Class: |
H01L 27/146 20060101
H01L027/146 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2013 |
JP |
2013-054588 |
Claims
1. A solid state imaging device comprising: a substrate, wherein
the substrate includes a photoelectric conversion unit that
generates a charge according to a light amount of incident light by
a pixel unit, an accumulation unit that divides the charge of the
pixel unit which is generated in the photoelectric conversion unit
and accumulates the charge, a first element isolation unit that is
formed at a boundary of the photoelectric conversion unit of the
pixel unit, and a second element isolation unit that is formed at a
boundary of the accumulation unit of a divided unit of the
pixel.
2. The solid state imaging device according to claim 1, wherein the
photoelectric conversion unit is formed on a side which is
irradiated with the incident light from the accumulation unit, and
the first element isolation unit is formed on the side which is
irradiated with the incident light from the second element
isolation unit.
3. The solid state imaging device according to claim 1, further
comprising: a light shielding unit that is arranged on the
substrate of the first element isolation unit to shield the
incident light.
4. The solid state imaging device according to claim 1, further
comprising: a color filter of a color that is arranged on the
substrate of the photoelectric conversion unit to be assigned to
the pixel corresponding to the photoelectric conversion unit.
5. The solid state imaging device according to claim 1, further
comprising: a lens that is arranged on the substrate of the
photoelectric conversion unit to concentrate the incident light to
the photoelectric conversion unit.
6. A manufacturing method for a manufacturing apparatus of a solid
state imaging device, comprising: forming a photoelectric
conversion unit that generates a charge according to a light amount
of incident light by a pixel unit on a substrate; forming an
accumulation unit that divides the charge of the pixel unit which
is generated in the photoelectric conversion unit and accumulates
the charge on the substrate; forming a first element isolation unit
that is formed at a boundary of the photoelectric conversion unit
of the pixel unit on the substrate; and forming a second element
isolation unit that is formed at a boundary of the accumulation
unit of a divided unit of the pixel on the substrate.
7. An electronic apparatus comprising: a substrate, wherein the
substrate includes a photoelectric conversion unit that generates a
charge according to a light amount of incident light by a pixel
unit, an accumulation unit that divides the charge of the pixel
unit which is generated in the photoelectric conversion unit and
accumulates the charge, a first element isolation unit that is
formed at a boundary of the photoelectric conversion unit of the
pixel unit, and a second element isolation unit that is formed at a
boundary of the accumulation unit of a divided unit of the pixel.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Japanese Priority
Patent Application JP 2013-054588 filed Mar. 18, 2013, the entire
contents of which are incorporated herein by reference.
BACKGROUND
[0002] The present disclosure relates to a solid state imaging
device and a manufacturing method, and an electronic apparatus, in
particular, to a solid state imaging device and a manufacturing
method, and an electronic apparatus which are able to prevent a
deterioration in transfer while suppressing a decrease in
sensitivity.
[0003] In recent years, in the solid state imaging device,
expanding an area of a light receiving surface by enlarging a pixel
size, in order to realize the high sensitivity has been considered.
However, when the pixel size increases, a transfer length becomes
long, and thus transfer efficiency deteriorates.
[0004] Therefore, there is disclosed a method that makes the
transfer length short by dividing the pixel and arranging a
transfer transistor with respect to each divided pixel and is able
to prevent the deterioration of the transfer efficiency along with
lowering a voltage (for example, see Japanese Unexamined Patent
Application Publication No. 2011-239070).
SUMMARY
[0005] However, in the method described above, since it is
necessary to form an element isolation unit that isolates the
divided pixel between the divided pixels, an opening area of a
photodiode is reduced and the sensitivity is decreased.
[0006] The present disclosure is made in view of such
circumstances, and thus is able to prevent the deterioration in the
transfer while suppressing the decrease in the sensitivity.
[0007] According to a first embodiment of the present disclosure,
there are provided a solid state imaging device and an electronic
apparatus each including a substrate, in which the substrate
includes a photoelectric conversion unit that generates a charge
according to a light amount of incident light by a pixel unit, an
accumulation unit that divides the charge of the pixel unit which
is generated in the photoelectric conversion unit and accumulates
the charge, a first element isolation unit that is formed at a
boundary of the photoelectric conversion unit of the pixel unit,
and a second element isolation unit that is formed at a boundary of
the accumulation unit of a divided unit of the pixel.
[0008] In the first embodiment of the present disclosure, the
photoelectric conversion unit generates the charge according to the
light amount of the incident light by the pixel unit, the
accumulation unit divides the charge of the pixel unit which is
generated in the photoelectric conversion unit and accumulates the
charge, the first element isolation unit is formed at the boundary
of the photoelectric conversion unit of the pixel unit, and the
second element isolation unit is formed at the boundary of the
accumulation unit of the divided unit of the pixel.
[0009] According to a second embodiment of the present disclosure,
there is provided a manufacturing method for a manufacturing
apparatus of a solid state imaging device, including forming a
photoelectric conversion unit that generates a charge according to
a light amount of incident light by a pixel unit on a substrate,
forming an accumulation unit that divides the charge of the pixel
unit which is generated in the photoelectric conversion unit and
accumulates the charge on the substrate, forming a first element
isolation unit that is formed at a boundary of the photoelectric
conversion unit of the pixel unit on the substrate, and forming a
second element isolation unit that is formed at a boundary of the
accumulation unit of a divided unit of the pixel on the
substrate.
[0010] In the second embodiment of the present disclosure, the
photoelectric conversion unit that generates the charge according
to the light amount of the incident light by the pixel unit is
formed on the substrate, the accumulation unit that divides the
charge of the pixel unit which is generated in the photoelectric
conversion unit and accumulates the charge is formed on the
substrate, the first element isolation unit that is formed at a
boundary of the photoelectric conversion unit of the pixel unit is
formed on the substrate and the second element isolation unit that
is formed at a boundary of the accumulation unit of the divided
unit of the pixel is formed on the substrate.
[0011] According to the first embodiment of the present disclosure,
it is possible to prevent the deterioration in the transfer while
suppressing the decrease in the sensitivity.
[0012] Furthermore, according to the second embodiment of the
present disclosure, it is possible to manufacture the solid state
imaging device that can prevent the deterioration in the transfer
while suppressing the decrease in the sensitivity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a plan view seen from an incident side of light of
a pixel array in a CMOS image sensor which is a back side
irradiation type;
[0014] FIG. 2 is a sectional view taken along the line II-II in
FIG. 1;
[0015] FIG. 3 is a sectional view illustrating an outline of a
potential state of each divided pixel, taken along the line III-III
in FIG. 2;
[0016] FIG. 4 is a sectional view illustrating the outline of the
potential state of each divided pixel, taken along the line IV-IV
in FIG. 2;
[0017] FIG. 5 is a block diagram illustrating a configuration
example of the CMOS image sensor which is the back side irradiation
type as a solid state imaging device according to a first
embodiment to which the present disclosure is applied;
[0018] FIG. 6 is a plan view seen from the incident side of the
light of a pixel array unit in FIG. 5;
[0019] FIG. 7 is a sectional view taken along the line VII-VII in
FIG. 6;
[0020] FIG. 8 is a sectional view illustrating the outline of the
potential state of each divided pixel, taken along the line
VIII-VIII in FIG. 7;
[0021] FIG. 9 is a sectional view illustrating the outline of the
potential state of each divided pixel, taken along the line IX-IX
in FIG. 7;
[0022] FIG. 10 is a diagram illustrating an example of a
manufacturing method for a periphery of a photodiode of the pixel
array unit by a manufacturing apparatus; and
[0023] FIG. 11 is a block diagram illustrating a configuration
example of an imaging device as an electronic apparatus to which
the present disclosure is applied.
DETAILED DESCRIPTION OF EMBODIMENTS
Premise of Present Disclosure
[0024] FIG. 1 is a plan view seen from an incident side of light of
a pixel array in a CMOS (Complementary Metal-Oxide Semiconductor)
image sensor which is a back side irradiation type as a solid state
imaging device when a pixel is divided into 2.times.2 pieces.
Furthermore, FIG. 2 is a sectional view taken along the line II-II
in FIG. 1.
[0025] In FIG. 1, for convenience of description, only the
2.times.2 pieces of the pixel which is arranged in the pixel array
are shown. In the example of FIG. 1, an arrangement of each pixel
is a Bayer array. That is, a pixel 11 of the upper left is the
pixel of red color (R), a pixel 12 of the upper right and a pixel
13 of the lower left are the pixels of green color (G), and a pixel
14 of the lower right is the pixel of blue color (B).
[0026] As shown in FIG. 1, each of the pixel 11 to the pixel 14 are
divided into 2.times.2 pieces, and are formed on a substrate
(semiconductor substrate) 10 of the pixel array. Specifically, the
pixel 11 is formed of the four pieces as the divided pixels 15-1 to
15-4, and the pixel 12 is formed of the four pieces as the divided
pixels 15-5 to 15-8. The pixel 13 and the pixel 14 are formed in
the same manner.
[0027] Hereinafter, when it is not necessary to distinguish between
the divided pixels 15-1 to 15-8 in particular, the divided pixels
15-1 to 15-8 are collectively referred to as a divided pixel 15.
Similarly, the pixels 11 to 14 are collectively referred to as a
pixel 11A.
[0028] Furthermore, as shown in FIG. 2, a photodiode 19 which is a
photoelectric conversion element or the like is arranged inside the
substrate 10 of the divided pixel 15. Moreover, inside the
substrate 10 at a boundary of the divided pixel 15, an element
isolation unit 20 is formed from the incident side (back side) of
the light of the substrate 10 to an opposite side thereof (surface
side).
[0029] In this manner, since the element isolation unit 20 is
arranged from the back side of the substrate 10 to the surface side
thereof, an opening unit 21 of the photodiode 19 is merely reduced
by the element isolation unit 20, in comparison with the case where
the element isolation unit 20 is not formed. As a result, the
sensitivity is decreased.
[0030] In FIG. 2, a solid line that is described in the photodiode
19 is a contour of a potential.
[0031] Furthermore, as shown in FIG. 1 and FIG. 2, a light
shielding metal 16 that shields incident light is arranged on the
back side of the substrate 10 of the element isolation unit 20. On
the back side of the substrate 10 of the photodiode 19 of each
divided pixel 15, a color filter 17 of the color which is assigned
to the pixel 11A including the divided pixel 15, and an on-chip
lens 18 that concentrates the incident light to the photodiode 19
are arranged in order from the substrate 10 side.
[0032] FIG. 3 is a sectional view illustrating an outline of a
potential state of each divided pixel 15, taken along the line
III-III in FIG. 2, and FIG. 4 is a sectional view illustrating the
outline of the potential state of each divided pixel 15, taken
along the line IV-IV in FIG. 2.
[0033] As shown in FIG. 3 and FIG. 4, the potential of the
photodiode 19 is low, and the potential of the element isolation
unit 20 is high. Moreover, the capacitance between side walls of
the element isolation unit 20 increases due to a formation of the
element isolation unit 20, and a saturation signal amount Qs of the
photodiode 19 increases.
[0034] However, as shown in FIG. 3 and FIG. 4, the potential of the
photodiode 19 toward the back side of the substrate 10 is shallow,
in comparison with the surface side of the substrate 10.
[0035] Therefore, in the embodiments of the present disclosure, the
element isolation unit 20 is formed on only the surface side of the
substrate 10. In this manner, even when the pixels 11 to 14 are
divided in order to prevent the deterioration in the transfer, it
is possible to maintain the area of the opening unit 21 of the
photodiode 19 and suppress the decrease in the sensitivity. That
is, it is possible to prevent the deterioration in the transfer
while suppressing the decrease in the sensitivity.
[0036] In addition, on the surface side of the substrate 10 where
the potential is deep and the capacitance is easy to be large, the
saturation signal amount Qs increases due to the capacitance
between the side walls of the element isolation unit 20, and, on
the back side of the substrate 10 where the potential is shallow
and the capacitance is hard to be large, it is possible to increase
the saturation signal amount Qs due to the volume of the photodiode
19. Accordingly, it is possible to increase the saturation signal
amount Qs efficiently, and improve a dynamic range.
First Embodiment
Configuration Example of Solid State Imaging Device According to an
Embodiment
[0037] FIG. 5 is a block diagram illustrating a configuration
example of the CMOS image sensor which is the back side irradiation
type as a solid state imaging device according to a first
embodiment to which the present disclosure is applied.
[0038] A CMOS image sensor 100 is configured by a pixel array unit
111, a vertical drive unit 112, a column processing unit 113, a
horizontal drive unit 114, a system control unit 115, a pixel drive
line 116, a vertical signal line 117, a signal processing unit 118
and a data storage unit 119.
[0039] The pixel array unit 111, the vertical drive unit 112, the
column processing unit 113, the horizontal drive unit 114, the
system control unit 115, the pixel drive line 116, the vertical
signal line 117, the signal processing unit 118 and the data
storage unit 119 are formed on the substrate (chip) which is not
shown in FIG. 5.
[0040] Furthermore, the CMOS image sensor 100 does not include the
signal processing unit 118 and the data storage unit 119, and, for
example, the signal processing unit 118 and the data storage unit
119 may be arranged as an external signal processing unit such as a
DSP (Digital Signal Processor) on the substrate other than the CMOS
image sensor 100.
[0041] The CMOS image sensor 100 images an image of a subject, and
outputs a pixel signal of each pixel of the image.
[0042] Specifically, in the pixel array unit 111, the pixels
including the photodiode such as the photoelectric conversion
element that generates a charge of a charge amount according to a
light amount of the incident light and accumulates the charge
therein, are two-dimensionally arranged in a matrix. Each of the
pixels is divided into plural divided pixels (2.times.2 pieces in
the embodiments).
[0043] Furthermore, in the pixel array unit 111, with respect to
the pixels in the matrix, the pixel drive line 116 is formed in the
left and right direction (row direction) of FIG. 5 for each row and
the vertical signal line 117 is formed in the up and down direction
(column direction) of FIG. 5 for each column. One end of the pixel
drive line 116 is connected to an output end (not shown)
corresponding to each row of the vertical drive unit 112.
[0044] The vertical drive unit 112 is configured by a shift
register, an address decoder or the like. The vertical drive unit
112 is a pixel drive unit that drives each pixel of the pixel array
unit 111 by a row unit or the like. The specific configuration of
the vertical drive unit 112 is not shown in FIG. 5, but the
vertical drive unit 112 has the configuration including two
scanning systems of a reading-out scanning system and a
sweeping-out scanning system.
[0045] The reading-out scanning system selects each row in order
and outputs a selection pulse from the output end which is
connected to the pixel drive line 116 of the selected row, so as to
read out the pixel signal from each pixel in order by the row
unit.
[0046] The sweeping-out scanning system precedes scanning of the
reading-out scanning system by a time of shutter speed and outputs
a control pulse from the output end which is connected to the pixel
drive line 116 of each row, in order to sweep out (reset) the
unnecessary charge from the photodiode. By the scanning of the
sweeping-out scanning system, a so-called electronic shutter
operation is performed in order for each row. Here, an operation to
discard the charge of the photodiode and start an exposure anew
(start the accumulation of the charge) is referred to as the
electronic shutter operation.
[0047] The pixel signal that is output from each pixel of the row
selected by the reading-out scanning system of the vertical drive
unit 112, is supplied to the column processing unit 113 through
each vertical signal line 117.
[0048] The column processing unit 113 includes a signal processing
circuit for each column of the pixel array unit 111. Each signal
processing circuit of the column processing unit 113 performs a
noise removal processing such as a CDS (Correlated Double Sampling)
processing and a signal processing such as an A/D conversion
processing, with respect to the pixel signal that is output through
the vertical signal line 117 from each pixel of the selected row.
By the CDS processing, a reset noise and the noise of a fixed
pattern peculiar to the pixel such as a threshold variation of an
amplification transistor, are removed. The column processing unit
113 temporarily holds the pixel signal after the signal
processing.
[0049] The horizontal drive unit 114 is configured by the shift
register, the address decoder or the like. The horizontal drive
unit 114 selects the signal processing circuit of the column
processing unit 113 in order. The pixel signal that is
signal-processed by each signal processing circuit of the column
processing unit 113, is output to the signal processing unit 118 in
order, due to the scanning which is selected by the horizontal
drive unit 114.
[0050] The system control unit 115 is configured by a timing
generator to generate various timing signals or the like. The
system control unit 115 controls the vertical drive unit 112, the
column processing unit 113 and the horizontal drive unit 114, based
on various timing signals which are generated by the timing
generator.
[0051] The signal processing unit 118 includes at least an addition
processing function. The signal processing unit 118 performs
various signal processings such as the addition processing, with
respect to the pixel signal which is output from the column
processing unit 113. At this time, as necessary, the signal
processing unit 118 stores an intermediate result of the signal
processing and the like in the data storage unit 119, and refers to
them at a necessary timing. The signal processing unit 118 outputs
the pixel signal after the signal processing.
Configuration Example of Pixel Array Unit
[0052] FIG. 6 is a plan view seen from the incident side of the
light of the pixel array unit 111 in FIG. 5, and FIG. 7 is a
sectional view taken along the line VII-VII in FIG. 6.
[0053] In FIG. 6, for the convenience of the description, only the
2.times.2 pieces of the pixel which is arranged in the pixel array
unit 111, are shown. In the example of FIG. 6, the arrangement of
each pixel is the Bayer array. That is, a pixel 131 of the upper
left is the pixel of the red color (R), a pixel 132 of the upper
right and a pixel 133 of the lower left are the pixels of the green
color (G), and a pixel 134 of the lower right is the pixel of the
blue color (B).
[0054] As shown in FIG. 6, each of the pixel 131 to the pixel 134
are divided into 2.times.2 pieces, and are formed on a substrate
130 of the pixel array unit 111. Specifically, the pixel 131 is
formed of the four pieces as the divided pixels 135-1 to 135-4, and
the pixel 132 is formed of the four pieces as the divided pixels
135-5 to 135-8. The pixel 133 and the pixel 134 are formed in the
same manner.
[0055] Hereinafter, when it is not necessary to distinguish between
the divided pixels 135-1 to 135-8 in particular, the divided pixels
135-1 to 135-8 are collectively referred to as a divided pixel 135.
Similarly, the pixels 131 to 134 are collectively referred to as a
pixel 131A.
[0056] Furthermore, as shown in FIG. 7, a photodiode 139 or the
like is arranged inside the substrate 130 of the divided pixel 135.
The photodiode 139 is configured by a photoelectric conversion unit
139A that is arranged by the pixel 131A unit on the back side of
the substrate 130 and an accumulation unit 139B that is arranged by
the divided pixel 135 unit on the surface side of the substrate
130.
[0057] The photoelectric conversion unit 139A generates the charge
according to the light amount of the incident light by the pixel
131A unit, and the accumulation unit 139B divides the charge of the
pixel 131A unit which is generated in the photoelectric conversion
unit 139A and accumulates the charge by the divided pixel 135 unit.
The charge which is accumulated by the accumulation unit 139B is
transferred by the divided pixel 135 unit. Accordingly, the
transfer length becomes short, and it is possible to prevent the
deterioration in the transfer.
[0058] An element isolation unit 140 is formed at the boundary of
the photoelectric conversion unit 139A of the pixel 131A unit, and
an element isolation unit 141 is formed at the boundary of the
accumulation unit 139B of the divided pixel 135 unit. Specifically,
the element isolation unit 141 is arranged by the divided pixel 135
unit, and formed only as a thickness (for example, 1.5 micrometers)
of the accumulation unit 139B from the surface side of the
substrate 130. On the other hand, the element isolation unit 140 is
arranged by the pixel 131A unit, and formed to the back side of the
substrate 130 while connecting to the element isolation unit 141 of
the pixel 131A unit.
[0059] That is, the element isolation unit 141 is formed at the
boundary of the photodiode 139 of each divided pixel 135, and the
element isolation unit 140 and the element isolation unit 141 are
formed at the boundary of the photodiode 19 of the pixel 131A.
[0060] As described above, the element isolation unit 141 which is
arranged at the boundary of each divided pixel 135 is not formed on
the back side of the substrate 130, and thus only the element
isolation unit 140 of the pixel 131A unit is formed on the back
side of the substrate 130. Consequently, the size of an opening
unit 142 of the photodiode 139 is the same size as the case of not
dividing the pixel, and it is possible to suppress the decrease in
the sensitivity.
[0061] In FIG. 7, the solid line that is described in the
photodiode 139 is the contour of the potential.
[0062] Furthermore, as shown in FIG. 6 and FIG. 7, a light
shielding metal 136 that shields the incident light is arranged on
the back side of the substrate 130 of the element isolation unit
140. On the back side of the substrate 130 of the photoelectric
conversion unit 139A of each pixel 131A, a color filter 137 of the
color which is assigned to the pixel 131A, and an on-chip lens 138
that concentrates the incident light to the photoelectric
conversion unit 139A are arranged in order from the substrate 130
side.
[0063] FIG. 8 is a sectional view illustrating the outline of the
potential state of each divided pixel 135, taken along the line
VIII-VIII in FIG. 7, and FIG. 9 is a sectional view illustrating
the outline of the potential state of each divided pixel 135, taken
along the line IX-IX in FIG. 7.
[0064] As shown in FIG. 8, on the surface side of the substrate
130, the potential of the accumulation unit 139B is low, and the
potential of the element isolation unit 141 of the divided pixel
135 unit is high. Moreover, as shown in FIG. 9, on the back side of
the substrate 130, the potential of the photoelectric conversion
unit 139A is low, and the potential of the element isolation unit
140 of the pixel 131A unit is high.
[0065] In addition, as shown in FIG. 8 and FIG. 9, the potential of
the photodiode 139 toward the surface side of the substrate 130 is
deep, in comparison with the back side of the substrate 130. In
other words, the capacitance is easy to be large on the surface
side of the substrate 130, and the capacitance is hard to be large
on the back side of the substrate 130.
[0066] Accordingly, in the same manner of the CMOS image sensor
100, when the element isolation unit 141 is formed by the divided
pixel 135 unit on the surface side of the substrate 130, the
saturation signal amount Qs efficiently increases due to the
capacitance between the side walls of the element isolation unit
141. Furthermore, in the same manner of the CMOS image sensor 100,
when the element isolation unit 141 is not arranged on the back
side of the substrate 130, the saturation signal amount Qs
efficiently increases due to the volume increase of the photodiode
139. As a result, it is possible to improve the dynamic range.
Manufacturing Method of Pixel Array Unit
[0067] FIG. 10 is a diagram illustrating an example of a
manufacturing method for manufacturing a periphery of the
photodiode 139 of the pixel array unit 111 by a manufacturing
apparatus.
[0068] As shown in FIG. 10, in a first process, the photodiode 139
which is configured of the photoelectric conversion unit 139A and
the accumulation unit 139B, is formed inside the substrate 130.
Therefore, a photoresist 151 is applied to the area corresponding
to the accumulation unit 139B of each divided pixel 135 in an upper
part of the substrate 130.
[0069] In a second process, an impurity 152 having a predetermined
thickness (for example, 1.5 micrometers) is implanted into the
boundary of the accumulation unit 139B to which the photoresist 151
is not supplied, by performing an ion implantation. The element
isolation unit 141 is formed in this manner, and a photoresist 153
is applied to the area corresponding to the photoelectric
conversion unit 139A of each pixel 131A of the upper part of the
substrate 130.
[0070] In a third process, by performing the ion implantation, an
impurity 154 is implanted into the back side of the substrate 130
of the element isolation unit 141 at the boundary of the
photoelectric conversion unit 139A to which the photoresist 153 is
not supplied, to the back side. Accordingly, the element isolation
unit 140 is formed on the element isolation unit 141 at the
boundary of the photoelectric conversion unit 139A of the pixel
131A.
[0071] As described above, the impurity is not implanted into the
back side of the substrate 130 of the element isolation unit 141,
other than the boundary of the photoelectric conversion unit 139A
of the pixel 131A. Consequently, it is possible to reduce the
amount of the impurity that is implanted into the substrate 130, in
comparison with the case where the element isolation unit 140 is
formed on the whole back side of the substrate 130 of the element
isolation unit 141, and prevent an occurrence of a white spot.
Configuration Example of Second Embodiment
Configuration Example of Electronic Apparatus According to an
Embodiment
[0072] FIG. 11 is a block diagram illustrating a configuration
example of an imaging device as an electronic apparatus to which
the present disclosure is applied.
[0073] An imaging device 500 of FIG. 11 is a video camera or a
digital still camera, for example. The imaging device 500 is
configured of an optical unit 501, a solid state imaging device
502, a DSP circuit 503, a frame memory 504, a display unit 505, a
recording unit 506, an operation unit 507 and a power supply unit
508. The DSP circuit 503, the frame memory 504, the display unit
505, the recording unit 506, the operation unit 507 and the power
supply unit 508, are connected to each other via a bus line
509.
[0074] The optical unit 501 is configured of a lens group or the
like. The optical unit 501 makes the image on an imaging surface of
the solid state imaging device 502 by capturing the incident light
(image light) from the subject. The solid state imaging device 502
is configured of the CMOS image sensor 100 described above. The
solid state imaging device 502 converts the light amount of the
incident light with which the image is made on the imaging surface
by the optical unit 501, into an electrical signal by the pixel
unit, and supplies the electrical signal as a pixel signal to the
DSP circuit 503.
[0075] The DSP circuit 503 performs a predetermined image
processing, with respect to the pixel signal which is supplied from
the solid state imaging device 502. The DSP circuit 503 supplies an
image signal after the image processing to the frame memory 504, by
a frame unit, and stores the image signal temporarily.
[0076] For example, the display unit 505 is configured of a panel
type display apparatus such as a liquid crystal panel and an
organic EL (Electro Luminescence) panel, and displays the image,
based on the pixel signal of the frame unit which is temporarily
stored in the frame memory 504.
[0077] The recording unit 506 is configured of a DVD (Digital
Versatile Disk), a flash memory or the like. The recording unit 506
reads out the pixel signal of the frame unit which is temporarily
stored in the frame memory 504, and records the pixel signal.
[0078] The operation unit 507 issues an operation instruction to
the imaging device 500 having various functions, with the operation
by a user. The power supply unit 508 properly supplies a power
source, with respect to the DSP circuit 503, the frame memory 504,
the display unit 505, the recording unit 506 and the operation unit
507.
[0079] The electronic apparatus to which the present technique is
applied, may be any type of the electronic apparatus, if the solid
state imaging device is used in an image capturing unit
(photoelectric conversion unit). In addition to the imaging device
500, the electronic apparatus is a portable terminal apparatus
having an imaging function, a copying machine in which the solid
state imaging device is used in an image reading unit, or the
like.
[0080] Moreover, the CMOS image sensor may have a form that is
formed as one chip, or a module type form with the imaging function
which is packaged including the optical unit or the like.
[0081] The embodiments of the present disclosure is not limited to
the embodiments described above, and various modifications are
possible within a range that does not deviate from the scope of the
present disclosure.
[0082] For example, the present disclosure may be applied to a
surface side irradiation type CMOS image sensor other than the back
side irradiation type CMOS image sensor, and the solid state
imaging device such as a CCD (Charge Coupled Device).
[0083] Furthermore, a position of the vertical direction to the
substrate 130 of the element isolation unit 141 may be suitable, if
the position corresponds to the area where the potential of the
photodiode 139 is relatively deep. The position of the vertical
direction to the substrate 130 of the element isolation unit 141 is
not limited to the position of 1.5 micrometers from the surface of
the substrate 130.
[0084] The present disclosure may be configured as follows.
[0085] (1) A solid state imaging device including: a substrate, in
which the substrate includes a photoelectric conversion unit that
generates a charge according to a light amount of incident light by
a pixel unit, an accumulation unit that divides the charge of the
pixel unit which is generated in the photoelectric conversion unit
and accumulates the charge, a first element isolation unit that is
formed at a boundary of the photoelectric conversion unit of the
pixel unit, and a second element isolation unit that is formed at a
boundary of the accumulation unit of a divided unit of the
pixel.
[0086] (2) The solid state imaging device according to the above
(1), in which the photoelectric conversion unit is formed on a side
which is irradiated with the incident light from the accumulation
unit, and the first element isolation unit is formed on the side
which is irradiated with the incident light from the second element
isolation unit.
[0087] (3) The solid state imaging device according to the above
(1) or (2), further including: a light shielding unit that is
arranged on the substrate of the first element isolation unit to
shield the incident light.
[0088] (4) The solid state imaging device according to any one of
the above (1) to (3), further including: a color filter of a color
that is arranged on the substrate of the photoelectric conversion
unit to be assigned to the pixel corresponding to the photoelectric
conversion unit.
[0089] (5) The solid state imaging device according to any one of
the above (1) to (4), further including: a lens that is arranged on
the substrate of the photoelectric conversion unit to concentrate
the incident light to the photoelectric conversion unit.
[0090] (6) A manufacturing method for a manufacturing apparatus of
a solid state imaging device, including: forming a photoelectric
conversion unit that generates a charge according to a light amount
of incident light by a pixel unit on a substrate; forming an
accumulation unit that divides the charge of the pixel unit which
is generated in the photoelectric conversion unit and accumulates
the charge on the substrate; forming a first element isolation unit
that is formed at a boundary of the photoelectric conversion unit
of the pixel unit on the substrate; and forming a second element
isolation unit that is formed at a boundary of the accumulation
unit of a divided unit of the pixel on the substrate.
[0091] (7) An electronic apparatus including: a substrate, in which
the substrate includes a photoelectric conversion unit that
generates a charge according to a light amount of incident light by
a pixel unit, an accumulation unit that divides the charge of the
pixel unit which is generated in the photoelectric conversion unit
and accumulates the charge, a first element isolation unit that is
formed at a boundary of the photoelectric conversion unit of the
pixel unit, and a second element isolation unit that is formed at a
boundary of the accumulation unit of a divided unit of the
pixel.
[0092] It should be understood by those skilled in the art that
various modifications, combinations, sub-combinations and
alterations may occur depending on design requirements and other
factors insofar as they are within the scope of the appended claims
or the equivalents thereof.
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